Excitation Gap from Optimized Correlation Functions in Quantum Monte Carlo Simulations

TL;DR

This paper introduces a method to optimize correlation functions in quantum Monte Carlo simulations, enabling more accurate and efficient extraction of excitation gaps in many-body quantum systems.

Contribution

The authors propose a practical prescription for optimizing correlation functions, improving gap measurements without significant computational overhead.

Findings

Optimized correlation functions yield more accurate gap estimates.

The method enhances signal-to-noise ratios in Monte Carlo simulations.

The procedure is computationally inexpensive and effective across various many-body systems.

Abstract

We give a prescription for finding optimized correlation functions for the extraction of the gap to the first excited state within quantum Monte Carlo simulations. We demonstrate that optimized correlation functions provide a more accurate reading of the gap when compared to other `non-optimized' correlation functions and are generally characterized by considerably larger signal-to-noise ratios. We also analyze the cost of the procedure and show that it is not computationally demanding. We illustrate the effectiveness of the proposed procedure by analyzing several exemplary many-body systems of interacting spin-1/2 particles.